<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <div>1</div>
  <div>2</div>
  <div>3</div>
  <div>4</div>
  <div>5</div>

  <script>
    var div = document.querySelectorAll('div')
    console.log(div); //NodeList(5) [div, div, div, div, div]
    div = Array.from(div);
    console.log(div); //(5) [div, div, div, div, div]


    var weiarr = {
      "0": "1",
      "1": "2",
      "length": 2
    }
    var arr = Array.from(weiarr, item => item * 2)
    console.log(arr); //(2) [2, 4]
  </script>
</body>

</html>